Auto Scaling Group with User Data Not working with cfn-signal

I have an Auto Scaling Group provisioned by SAM (Serverless Application Model) which is similar to Cloud Formation, which provisions Windows EC2 instances. I have User Data being executed as powershell scripts. Sometimes some scripts fail. If the PS scripts fail as part of User Data Execution, I want to roll back the stack. For that, I understand there is cfn-init and cfn-signal. I have the following code in the CloudFormation AutoScalingGroup template. MyASG: Type: AWS::AutoScaling::AutoScalingGroup CreationPolicy: ResourceSignal: Count: 2 Timeout: PT15M UpdatePolicy: AutoScalingRollingUpdate: MinInstancesInService: '1' MaxBatchSize: '1' PauseTime: PT12M5S WaitOnResourceSignals: true SuspendProcesses: - HealthCheck - ReplaceUnhealthy - AZRebalance - AlarmNotification - ScheduledActions

In my UserData, I have the following lines. ` UserData: Fn::Base64: !Sub | <powershell> # START LOG. $LASTEXITCODE=0 $ErrorActionPreference = "Stop" cfn-init.exe -v --stack ${AWS::StackName} --resource MyASG --region ${AWS::Region} cfn-signal.exe -e **%ERRORLEVEL% **--stack ${AWS::StackName} --resource MyASG --region ${AWS::Region} $timestamp = Get-Date -Format yyyyMMdd-hhmm Start-Transcript -Path $logpath -Force

          #  DOWNLOAD FILES
          write "Downloading files from S3 bucket"
          Get-S3Object -BucketName $bucketName -KeyPrefix ${myS3Path}/ | Read-S3Object -Folder "C:\"

          #  CALL Custom Exe to execute some PS scripts
          write "running command '.\custom.exe 
          .\custom.exe "config.yml" --region "${AWS::Region}"
          if ( $LASTEXITCODE -ne 0 ) { write-error "Custom exe exit code '$LASTEXITCODE' does not indicate success. Refer to logs for details." }              
        </powershell>  `

In the above PS code, if I use %ERRORLEVEL% in cfn-signal, it always returns 0 success signals, even when there are no errors (verified the userdataexecution.log), whereas if I use 0 in place of %ERRORLEVEL%, it always returns 2 of 2 success signals, even when there are errors. I am confused on how to use this whole thing or get this working or achieve this functionality. Any help will be appreciated.